Hello Perl300,

According to RedHat Forum on similar case (see here Getting an error "curl: (60) Peer certificate cannot be authenticated with known CA certificates" when trying to curl a site that has a VALID SSL certificate) the problem was fixed by updating the CA.

Sample of Resolution:

Update the ca-certificates package to the version provided in RHEA-201
+3:1596 (ca-certificates-2013.1.94-65.0.el6) or a newer version
[download]

Try updating Curl and also installing / updating the CA:

yum update curl -y
yum install ca-certificates -y
[download]

Let us know if it works after that. BR / Thanos